A system for and method of modulating and demodulating a communication signal using differential quadrature phase shift keying (DQPSK) can include, upon receiving an inbound communication signal, demodulating the inbound communication signal by obtaining Pi/4 differential quadrature phase shift keying (DQPSK) symbols, translating the Pi/4 DQPSK symbols into quadrature phase shift keying (QPSK) symbols, and mapping the QPSK symbols to a pair of bits. Upon initiating an outbound communication signal, the system and method can include modulating the outbound communication signal by obtaining communication bits indicative of the outbound communication signal, translating the communication bits to three communication bits, and mapping the translated bits to DQPSK symbols.
Legal claims defining the scope of protection, as filed with the USPTO.
2. The modem of claim 1 , wherein the translation of the communication bits to three communication bits comprises performing an XOR operation.
3. The modem of claim 1 , wherein the mapping of QPSK symbols to a pair of bits performed by the processing unit comprises utilizing a lookup table to map the QPSK symbols to a pair of bits.
4. The modem of claim 1 , wherein the storage device comprises look up tables having the following values stored therein: QPSK Symbol Input Two Bits Output Pi/4 00 3 Pi/4 01 −3 Pi/4 10 −Pi/4 11 and Bit Combination Real Imaginary 000 0 1 001 −0.707 0.707 010 −1 0 011 −0.707 −0.707 100 0 −1 101 0.707 −0.707 110 1 0 111 0.707 0.707.
6. The system of claim 5 , wherein the means for translating the communication bits to three communication bits does not involve a complex multiplication operation.
7. The system of claim 5 , wherein the means for translating the communication bits to three communication bits comprises means for performing an XOR operation.
8. The system of claim 5 , wherein a phase of a first symbol is not known and a phase of a predecessor symbol is known.
9. The system of claim 5 , wherein the means for mapping the QPSK symbols to a pair of bits comprises means for utilizing a lookup table to map the QPSK symbols to a pair of bits.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
August 13, 2001
September 12, 2006
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